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Incised valleys are commonly investigated based on outcrop, modern setting and seismic data, which are often limited by data availability, especially for broad (ca >100 km wide) shelf settings. Consequently, few have described complete depositional systems of the incised valleys, especially those linked to their corresponding modern rivers in a source‐to‐sink framework to determine comprehensive controlling factors. This study documents Late Quaternary incised valleys and their characteristics in the Balingian – Central Luconia shelf based on regionally‐extensive three‐dimensional seismic data, two‐dimensional high‐resolution seismic data and boreholes. The three‐dimensional seismic data show that the main Tatau incised valley and tributary Suai incised valley fed the Tatau–Suai shelf‐edge delta. The Tatau incised valley is interpreted as the main incised valley based on its broader width, thicker infill, two‐tier stratigraphic architecture and its larger drainage basin area compared to the tributary Suai incised valley. The Tatau incised valley shifted its direction towards an active tectonic lineament (West Baram Line) and bypassed sediments to the deep‐water via a series of upper slope channels. The Tatau incised valley system comprises the following elements: (i) an upstream segment characterized by rivers dissecting an uplifted hinterland comprising Neogene sedimentary rocks, humid‐tropical vegetation, monsoonal climate, extremely high river discharge and sediment supply; (ii) a midstream segment comprising an emergent, vegetated (tropical rainforest to mangroves) and relatively narrow (ca 150 to 200 km wide) shelf, which was characterized by basinward‐increasing, tectonically‐driven accommodation space, valley incision and deposition; (iii) a downstream segment with increasing tidal‐influence where the Tatau and its tributary valley merged; and (iv) a short (15 to 20 km), narrow (10 to 15 km), tectonically‐controlled shelf‐edge delta and channelized upper slope. This study demonstrates the value of documenting an incised valley system in the context of its broader source‐to‐sink setting, which may provide a useful analogue for ancient incised valleys in comparable geological settings. [ABSTRACT FROM AUTHOR]

In submarine settings, the growth of structurally influenced topography can play a decisive role in controlling the routing of sediments from shelf‐edge to deep water, and can determine depositional architectures and sediment characteristics. Here we use well‐constrained examples from the deep water Niger Delta, where gravity‐driven deformation has resulted in the development of a large fold and thrust belt, to illustrate how spatial and temporal variations in the rate of deformation have controlled the nature and locus of contrasting depositional styles. Published work in the study area using 3D seismic data has quantified the growth history of the thrust‐related folds at multiple locations using line‐length‐balancing, enabling cumulative strain for individual structures over time and along‐strike to be obtained. We integrate this information with seismic interpretation and facies analysis, focusing on the interval of maximum deformation (15 to 3.7 Ma), where maximum strain rates reached 7%/Ma. Within this interval, we observe a vertical change in depositional architecture where: (1) leveed‐confined and linear channels pass upward in to (2) ponded lobes with erosionally confined channels and finally (3) channelised sheets. Our analysis demonstrate that this change is tectonically induced and diachronous across the fault array, and we characterise the extent to which structural growth controls both the distribution and the architecture of the turbidite deposits in such settings. In particular, we show that leveed‐confined channels exist when they can exploit strain minima between growing faults or at their lateral tips. Conversely, as a result of fault linkage and increased strain rates submarine channels become erosional and may be forced to cross folds at their strain maxima (crests), where their pathways are influenced by across‐strike variations in shortening for individual structures. Our results enable us to propose new conceptual models of submarine channel deposition in structurally complex margins, and provide new insights into the magnitude of fault interaction needed to alter depositional style from leveed to erosionally confined channels, or to deflect seabed systems around growing structures. [ABSTRACT FROM AUTHOR]

Sandstone intrusions are found in all sedimentary environments but have been reported most commonly from deep-water settings. They also appear to be more frequently developed in tectonically active settings where applied tectonic stresses facilitate development of high fluid pressures within the sediments. A variety of mechanisms have been cited as triggers for clastic intrusions. These include seismicity induced liquefaction, application of tectonic stresses, excess pore fluid pressures generated by deposition-related processes and the influx of an overpressured fluid from deeper within the basin into a shallow sand body. The formation of sandstone dykes and sills is investigated here by considering them as natural hydraulic fractures. When the seal on an unconsolidated, overpressured sand body fails the resulting steep hydraulic gradient may cause the sand to fluidize. The fluidized slurry can then inject along pre-existing or new fractures to form elastic intrusions. The scale and the geometry of an intrusive complex is governed by the stress state, depth and pre-existing joints or faults within the sedimentary succession, as well as the nature of the host sediments. For the simplest tectonic setting, where the maximum stress in a basin is vertical (gravitational loading), small irregular intrusions commonly result in the formation of sills at shallow depths within a few metres of the surface, whereas at greater depth dykes and sills forming clastic intrusion networks are more typical. A simple relationship is derived to calculate the maximum burial depth at which a dyke-sill complex forms as a function of the source-bed to sill height, the bulk density of the surrounding sediments, and the ratio of the vertical to horizontal effective stresses, [K.sub.0]. When applied to three examples of large-scale dyke-sill complexes developed within Paleocene and Eocene deep-water reservoir sand bodies of the North Sea, maximum burial depths in a range of 375 to c. 500 m, 450-700 m and 550-850 m are estimated for intrusion of each of the three complexes. Keywords: soft sediment deformation mechanism, sandstone dykes, sandstone sills, sand volcanoes.

The Sierra Espuna in the Betic Cordillera in southern Spain was compressively deformed, and this continued till the Miocene times. The deformation reveals kinematics that correspond with those that were observed between the Eocene and the initial period of Miocene. The Sierra Espuna's kinematics reveal that it was the center point of oblique convergence between early and middle Miocene periods. There was late Eocene thrusting from the Southeast to the South in the Sierra Espuna, as revealed by paleomagnetic data.

The processes and deposits of deep‐water submarine channels are known to be influenced by a wide variety of controlling factors, both allocyclic and autocyclic. However, unlike their fluvial counterparts whose dynamics are well‐studied, the factors that control the long‐term behaviour of submarine channels, particularly on slopes undergoing active deformation, remain poorly understood. We combine seismic techniques with concepts from landscape dynamics to investigate quantitatively how the growth of gravitational‐collapse structures at or near the seabed in the Niger Delta have influenced the morphology of submarine channels along their length from the shelf edge to their deep‐water counterpart. From a three dimensional (3D), time‐migrated seismic‐reflection volume, which extends over 120 km from the shelf edge to the base of slope, we mapped the present‐day geomorphic expression of two submarine channels and active structures at the seabed, and created a Digital Elevation Model (DEM). A second geomorphic surface and DEM raster—interpreted to closer approximate the most recent active channel geometries—were created through removing the thickness of hemipelagic drape across the study area. The DEM rasters were used to extract the longitudinal profiles of channel systems with seabed expression, and we evaluate the evolution of channel widths, depths and slopes at fixed intervals downslope as the channels interact with growing structures. Results show that the channel long profiles have a relatively linear form with localized steepening associated with seabed structures. We demonstrate that channel morphologies and their constituent architectural elements are sensitive to active seafloor deformation, and we use the geomorphic data to infer a likely distribution of bed shear stresses and flow velocities from the shelf edge to deep water. Our results give new insights into the erosional dynamics of submarine channels, allow us to quantify the extent to which submarine channels can keep pace with growing structures, and help us to constrain the delivery and distribution of sediment to deep‐water settings. [ABSTRACT FROM AUTHOR]